This invention relates to an image transfer element for the thermal transfer of images. In particular, this invention relates to an image transfer element that is capable of forming a multicolored image on a variety of substrates using a variety of imaging devices and to its method of use.
Although the rapid growth of color printers and copiers has brought convenience and popularity to color imaging on flat and thin substrates such as papers and films, there is still a high demand for personalized color images on substrates that can not be fed through printers or copier. Such substrates include, for example, cloth, wood, leather, ceramic cups, ceramic tiles, glasses, metals, and hard plastics.
These substrates are typically imaged by an image transfer process. In this process, a temporary carrier or image transfer element is imaged with a mirror image of the desired image. The image is then transferred to the desired substrate by the application of heat and/or pressure. These processes have the advantage of not requiring a separate adhesive layer to adhere the image to the substrate.
Image transfer technology can be divided into two major categories: the transfer of sublimable dye molecules and the transfer of colorant-containing layers. Dye-sublimation requires specialty printers and specially designed receiving layers. In addition, dyes that have been specially designed for dye sublimation must be used. These disadvantages limit the use of dye sublimation technology.
The transfer of colorant-containing layers, on the other hand, has wide applications. There is little or no limitation on the imaging technique. The mirror image can be formed on an image-receiving layer by, for example, a laser printer, a wax thermal transfer printer, a phase-change solid ink jet printer, a liquid ink jet printer, a photocopier, or even by hand drawing. The image, along with the image-receiving layer, is transferred to the desired substrate by heat and/or pressure. Good adhesion can be achieved by carefully designing the image-receiving layer to obtain permanent chemical and/or physical bonding between the image-receiving layer and the substrate.
Image transfer has been described, for example, in Kronzer, U.S. Pat. Nos. 6,200,688, 6,113,725, 5,501,902, and 5,271,990. However, there are several disadvantages of these techniques. The major drawback is low durability of the transferred image. For example, when an image-containing image-receiving layer is transferred to a fabric, the image-receiving layer usually sits on the surface of the fabric, resulting in a raised image with poor washability and stress cracks.
Hare, U.S. Pat. Nos. 6,083,656 and 6,087,061, proposes ironing the image after each washing and drying cycle. However, this solution is not only cumbersome, it poses additional problems. Repeated ironing at high temperature usually causes the yellowing of the image transfer layer.
Another major drawback of image transfer to fabric is the undesirable plastic-feel of the transferred image and image transfer layer. This stiffness is caused by a combination of high melting point of the materials in the image transfer layer and the lack of penetration of these materials into the fabric during and after the heat transfer process.
Thus a need exits for an image transfer element that provides an image that has great durability, is easy to apply, has a soft fabric feel, and is compatible with a variety of printers.
The invention is an image transfer element that provides an image that has great durability, is easy to apply, has a soft fabric feel, and is compatible with a variety of printers. The image transfer element comprises:
a releasable support, and
an image-receiving layer over the support; in which:
the image-receiving layer comprises a film-forming polymeric binder and particles of a thermoplastic polymer;
the thermoplastic polymer has a Tm of about 50xc2x0 C. to about 200xc2x0 C.;
the particles of the thermoplastic polymer have a particle size of about 1 to about 150 microns; and
the film-forming polymeric binder comprises about 5 to about 30 vol % of the image transfer layer, based on the volume of the particles of the thermoplastic polymer present in the layer.
In another embodiment of the invention, the image-receiving layer additionally comprises a barrier layer between the releasable support and the image-receiving layer.
In another aspect, the invention is a method for forming an imaged article using the image transfer element. In yet another aspect, the invention is an imaged article formed by the method of the invention.